Description (adapted from the PI abstract): The long term objective is to understand fundamental molecular organization of the projection of the vestibular efferent neurons to the vestibular periphery. The proposal addresses 4 questions: 1) what are the topographic distributions of expressed genes and proteins for transmitter signaling in the rat and human vestibular end-organs and primary afferent ganglia; 2) what are the full length cDNA sequences encoding the mRNAs subserving the efferent/afferent interaction in the vestibular periphery; 3) what is the chromosome location and genomic sequence for each of these genes and how are they processes to yield these cDNAs; and 4) what changes occur in these genes during the aging process.